Thanks Jens for your comments.
On Mon, 8 Jul 2019 at 21:09, Jens Wiklander <jens.wiklander@xxxxxxxxxx> wrote:
>
> Hi Sumit,
>
> On Thu, Jun 13, 2019 at 04:00:29PM +0530, Sumit Garg wrote:
> > There are use-cases where user-space shouldn't be allowed to communicate
> > directly with a TEE device which is dedicated to provide a specific
> > service for a kernel client. So add a private login method for kernel
> > clients and disallow user-space to open-session using this login method.
> >
> > Signed-off-by: Sumit Garg <sumit.garg@xxxxxxxxxx>
> > ---
> > drivers/tee/tee_core.c | 6 ++++++
> > include/uapi/linux/tee.h | 2 ++
> > 2 files changed, 8 insertions(+)
> >
> > diff --git a/drivers/tee/tee_core.c b/drivers/tee/tee_core.c
> > index 0f16d9f..4581bd1 100644
> > --- a/drivers/tee/tee_core.c
> > +++ b/drivers/tee/tee_core.c
> > @@ -334,6 +334,12 @@ static int tee_ioctl_open_session(struct tee_context *ctx,
> > goto out;
> > }
> >
> > + if (arg.clnt_login == TEE_IOCTL_LOGIN_REE_KERNEL) {
> TEE_IOCTL_LOGIN_REE_KERNEL is defined as 0x80000000 which is in the
> range specified and implementation defined by the GP spec. I wonder if
> we shouldn't filter the entire implementation defined range instead of
> just this value.
Agree. Will rather check for entire implementation defined range:
0x80000000 - 0xFFFFFFFF.
>
> > + pr_err("login method not allowed for user-space client\n");
> pr_debug(), if it's needed at all.
>
Ok will use pr_debug() instead.
> > + rc = -EPERM;
> > + goto out;
> > + }
> > +
> > rc = ctx->teedev->desc->ops->open_session(ctx, &arg, params);
> > if (rc)
> > goto out;
> > diff --git a/include/uapi/linux/tee.h b/include/uapi/linux/tee.h
> > index 4b9eb06..f33c69c 100644
> > --- a/include/uapi/linux/tee.h
> > +++ b/include/uapi/linux/tee.h
> > @@ -172,6 +172,8 @@ struct tee_ioctl_buf_data {
> > #define TEE_IOCTL_LOGIN_APPLICATION 4
> > #define TEE_IOCTL_LOGIN_USER_APPLICATION 5
> > #define TEE_IOCTL_LOGIN_GROUP_APPLICATION 6
> > +/* Private login method for REE kernel clients */
> It's worth noting that this is filtered by the TEE framework, compared
> to everything else which is treated opaquely.
>
IIUC, you are referring to login filter in optee_os. Change to prevent
filter for this login method is part of this PR [1].
[1] https://github.com/OP-TEE/optee_os/pull/3082
-Sumit
> > +#define TEE_IOCTL_LOGIN_REE_KERNEL 0x80000000
> >
> > /**
> > * struct tee_ioctl_param - parameter
> > --
> > 2.7.4
> >
>
> Thanks,
> Jens
